How can I get my Job Title changed oin my Visa

Are you sure the job is of Marketing Manager? a reputable company would not pull such a move.

Check the authenticity of the company

In addition to hamudi - you need to know that visa profession cannot be changed in the local country , rather the company need to do it in KSA with MOFA / MOL from where the visa is  issued. This is usually a time consuming process.

So unless the job is of actual Marketing Manager you should be in a stronger position to ask them to change the profession now itself before coming to KSA or else it will take months to rectify.

People have been duped before, just make sure you won't be asked to work at a retail store and brand it as marketing manager

LOL. some engineers come to saudi and exit Saudi  as doctors.

LOL. IT guy, with technician visa, working as Marketing Expert.

There is no Marketing Manager visa for Asian expats,  they will get you in using skilled labor visa. Once you are in KSA, then you can request to change your visa type to another that you prefer. Good luck.